JP2000329305A - Boiler including heat absorption fin intersecting combustion gas flow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of absorption of heat in a shell and tube once-through boiler adapted such that combustion gas is flowed vertically to a combustion gas passage provided between conduit lines of inner and outer two lines. SOLUTION: A shell and tube once-through boiler is adapted such that an annular upper header 1 and a lower header 2 are coupled therebetween through an inside conduit 3 and an outside conduit 4, and a combustion gas passage 7 is provided between the inside conduit and the outside conduit, through which passage combustion gas is flowed vertically. In the boiler, heat absorption fins 11 of multiple stages are provided at a portion facing the combustion gas passage 7 between the inside conduit 3 and the outside conduit 4 so as to intersect a combustion gas flow. The heat absorption fins 11 are provided at the same heights for the inside conduit 3 and the outside conduit 4, so that there are provided many stages of contraction sections having a cross sectional area of the combustion gas passage with the heat absorption fins 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-tube once-through boiler for vertically flowing combustion gas in a combustion gas passage provided between an inner water pipe row and an outer water pipe row. The present invention relates to a boiler having heat absorbing fins crossing a gas flow.

[0002]

2. Description of the Related Art An annular upper header is provided at an upper portion, and an annular lower header is provided at a lower portion. An upper and lower header is connected by a number of vertical water pipes in two rows inside and outside, and adjacent water pipes in each water pipe row are connected. By closing the space except for the part that provides the smoke vent at the end of the water pipe,
A combustion gas passage is provided between the inner water pipe row and the outer water pipe row, and the combustion gas passage is connected to a combustion chamber in the center of the boiler by an inner smoke port provided at an end of the inner water pipe, and the inner smoke port and the pipe axial direction. 2. Description of the Related Art There is known a multi-tube once-through boiler which is connected to a flue by an outer smoke passage provided at an end of an outer water pipe on the opposite side, and in which a combustion gas flows vertically in a combustion gas passage.

In a boiler, it is desirable that the difference in the amount of heat absorbed in each water pipe is small. However, in the case of the above boiler,
Since the inner water pipe faces the combustion chamber, it can absorb a lot of heat, whereas the heat transfer surface of the outer water pipe is only the part facing the combustion gas passage. It absorbs less heat than the inner water pipe. Also, since it is necessary to increase the amount of heat absorption in order to improve the efficiency of the boiler, the heat transfer area is increased by providing heat absorbing fins in the portion of the outer water pipe facing the combustion gas passage, so that the outer water pipe can be used. , The amount of heat absorption was increased.

When heat absorbing fins are provided on the outer water pipe as shown in FIG. 4, the heat transfer area of the outer water pipe increases, so that the heat absorption of the outer water pipe increases, and the heat absorption in the inner and outer water pipe rows. Can be reduced and the amount of heat absorption can be increased. However, if the heat absorbing fins are provided, the combustion gas flow becomes resistance to the combustion gas flow, so that the combustion gas flow flows along the smooth inner water pipe surface without resistance, and the combustion gas flow flowing on the outer water pipe side where resistance is generated. Decreases accordingly. And since there is little combustion gas flow entering the part sandwiched by the heat absorbing fins,
The amount of heat absorption at the root of the heat absorbing fin 11 and the surface of the outer water tube 4 was small, and the effect of providing the heat absorbing fin 11 could not be sufficiently obtained.

[0005]

An object of the present invention is to provide a multi-tube once-through boiler having a structure in which combustion gas flows vertically through a combustion gas passage provided between two inner and outer water pipe rows. And to increase the heat absorption.

[0006]

SUMMARY OF THE INVENTION An annular upper header and a lower header are connected by an inner water pipe and an outer water pipe, and a combustion gas passage is provided between the inner water pipe and the outer water pipe. In the multi-tube once-through boiler configured to flow the combustion gas, a plurality of heat absorbing fins are provided at portions of the inner water pipe and the outer water pipe facing the combustion gas passage so as to cross the combustion gas flow. By providing the heat absorbing fins at the same height position in the inner water pipe and the outer water pipe, a large number of reduced portions of the combustion gas passage cross-sectional area due to the heat absorbing fins are provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a boiler embodying the present invention,
2 is a cross-sectional view taken along line AA of FIG. 1, FIG. 3 is a schematic diagram of a combustion gas flow in a combustion gas passage according to the present invention, and FIG. 4 is a schematic diagram of a combustion gas flow in a conventional combustion gas passage. It is. An annular upper header 1 is provided at the upper part of the can body, and an annular lower header 2 is also provided at the lower part. A plurality of annular inner water pipes 3 and outer water pipes 4 are connected between the upper and lower headers. I have. The inner water pipe 3 and the outer water pipe 4 are formed by a closing fin 8 parallel to the pipe axis direction between the adjacent water pipes at portions other than the end of the water pipe where the inner smoke port 5 and the outer smoke port 6 are provided. It is closed, and a combustion gas passage 7 is formed between the inner water pipe 3 and the outer water pipe 4. The central portion of the boiler surrounded by the inner water pipe 3 is a combustion chamber 9.
0 is provided.

The lower part of the inner water pipe is provided with an inner smoke passage 5 having no closing fin 8 so as to surround the combustion chamber 9. The inner smoke passage 5 connects the combustion chamber 9 and the combustion gas passage 7. The combustion gas generated in the combustion chamber 9 enters the combustion gas passage 7 through the inner smoke passage 5 and
Flowing upwards. An outer smoke passage 6 having no closing fins 8 is also provided in the upper part of the outer water pipe, and the combustion exhaust gas sent through the combustion gas passage 7 is taken out in the circumferential direction of the boiler through the outer smoke passage 6, and then the combustion exhaust gas is exhausted. Are assembled and exhausted from the flue.

On the surfaces of the inner water pipe 3 and the outer water pipe 4 facing the combustion gas passages, a number of fan-shaped heat absorbing fins 11 are provided so that the heat absorbing surfaces intersect the combustion gas flow. deep. The heat absorbing fins 11 include the inner water pipe 3 and the outer water pipe 4.
And the heat absorbing fins 11 form the reduced cross-sectional area of the combustion gas passage. The heat absorbing fins 11 connected to the inner water pipe 3 and the outer water pipe 4 are heat absorbing fins of the same shape, but one heat absorbing fin is connected to each of the inner water pipes 3 at each stage.
, Two heat absorbing fins are connected to each stage.

When the burner 10 is burned, high-temperature combustion gas is generated in the combustion chamber 9, and the combustion gas first heats the surface of the inner water pipe 3 on the combustion chamber 9 side. Subsequently, the combustion gas reaches the inside of the combustion gas passage 7 from the inner smoke passage 5 and flows at a high speed in the combustion gas passage 7 upward. Since the heat absorbing fins 11 are provided at the same height in the portions of the inner water pipe 3 and the outer water pipe 4 facing the combustion gas passage 7 so as to intersect with the combustion gas flow. The cross-sectional area of the passage 7 is alternately reduced in the portion where the heat absorbing fins 11 are reduced and expanded in the portion where the heat absorbing fins 11 are not provided.

The reduced portion of the combustion gas passage becomes a resistance when the flow of the combustion gas passes, and generates a pressure loss. Therefore, before the combustion gas passage reducing portion, a flow of the combustion gas is formed not toward the combustion gas passage reducing portion but toward the root direction of the heat absorbing fin 11 whose pressure is relatively low. . The combustion gas that has reached the root of the heat absorbing fin 11 heats the root of the heat absorbing fin 11 and the raw tube on the surface of the water pipe, and also absorbs much heat at the root of the heat absorbing fin 11 and the surface of the water pipe. Therefore, the amount of heat absorption increases.

When the inner water pipe 3 is a bare pipe as shown in FIG. 4, the flow of combustion gas reaching the root of the heat absorbing fins 11 is small, and the effect of providing the heat absorbing fins 11 cannot be sufficiently obtained. Was. However, the inner water pipe 3 and the outer water pipe 4
By providing the heat absorbing fins 11 at the same height position and providing the combustion gas passage reducing portion, the flow of the combustion gas proceeds in the root direction of the heat absorbing fins 11 and the heat absorption amount can be increased. Become like

The inner water pipe 3 absorbs more heat than the outer water pipe 4 because it faces the combustion chamber 9, but the difference in heat absorption between the inner water pipe 3 and the outer water pipe 4 is smaller. Is desirable. By making the area of the heat absorbing fins 11 provided on the outer water pipe 4 larger than the area of the heat absorbing fins 11 provided on the inner water pipe 3, the amount of heat absorption in the outer water pipe 4 can be increased by the inner water pipe 3. The heat absorption amount can be made larger than the increase amount, and the difference in heat absorption amount between the inner water pipe 3 and the outer water pipe 4 can be made smaller.

[0014]

By implementing the present invention, the amount of heat absorbed from the root portion of the heat absorbing fins and the tube portion on the surface of the water pipe can be increased, and the boiler efficiency can be improved. Further, since the amount of heat absorption in the outer water pipe is particularly increased, the difference in the amount of heat absorption between the inner water pipe and the outer water pipe can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a boiler according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic view of a combustion gas flow in a combustion gas passage according to the present invention.

FIG. 4 is a schematic diagram of a combustion gas flow in a combustion gas passage in a conventional case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper header 2 Lower header 3 Inner water pipe 4 Outer water pipe 5 Inner smoke vent 6 Outer smoke vent 7 Burning gas passage 8 Closing fin 9 Combustion chamber 10 Burner 11 Heat absorption fin

Claims (2)

[Claims] An annular upper header is provided at an upper part, and an annular lower header is also provided at a lower part. The upper and lower headers are connected by a plurality of vertical water pipes of two rows inside and outside, and adjacent water pipes in each water pipe row. Between the inner water pipe row and the outer water pipe row, and the combustion gas passage is provided on the inner water pipe end provided at the end of the inner water pipe. The chimney connects to the combustion chamber in the center of the boiler, and the inner chimney connects to the flue by the outer chimney provided at the end of the outer water pipe opposite the pipe axis direction. In the multi-tube once-through boiler configured to flow the combustion gas, a plurality of heat absorbing fins are provided at portions of the inner water pipe and the outer water pipe facing the combustion gas passage so as to cross the combustion gas flow. The heat absorbing fins have the same height in the inner water pipe and the outer water pipe. A boiler having heat absorbing fins crossing the combustion gas flow, wherein the heat absorbing fins are provided at a plurality of positions to reduce the sectional area of the combustion gas passage by the heat absorbing fins. 2. A boiler having heat absorbing fins crossing the combustion gas flow according to claim 1, wherein a total area of the heat absorbing fins connected to the outer water pipe side is equal to a heat area connected to the inner water pipe side. A boiler having heat absorbing fins intersecting a combustion gas flow, wherein the heat absorbing fins have a larger area than the total area of the absorbing fins.